Cause
User attempt to reuse lower-bound partition of the partitions being merged which is illegal
User attempt to reuse lower-bound partition of the partitions being merged which is illegal
Use the higher-bound partition to be the resulting partition or specify a new partition name
Try the following links for this error:
http://docs.oracle.com/cd/E16655_01/server.121/e26079/e12700.htm
https://community.oracle.com/message/3229900
Browse all solutions to database errors from Oracle, MS SQL, or MySQL